Hurricane Henri ( ) was a tropical cyclone that impacted the Northeastern United States. The eighth named storm and third hurricane of the 2021 Atlantic hurricane season, Henri developed from a well-defined low-pressure system north-northeast of Bermuda, becoming a tropical depression on August 16. Nearly a day later, the system strengthened into Tropical Storm Henri. Henri continued to move south, and later southwest before strengthening steadily, reaching its initial peak intensity with winds of and a pressure of early on August 19. Soon after, strong wind shear weakened Henri slightly. Eventually, on August 21, Henri strengthened into a Category 1 hurricane, before weakening back to a tropical storm and making landfall in Westerly, Rhode Island, on August 22, making it the second tropical cyclone to make landfall in the U.S. state of Rhode Island during the season, seven weeks after Elsa. It proceeded to move west-northwestward, weakening into a tropical depression while slowing down later that day. On August 23, Henri degenerated into a remnant low over New England, before dissipating the next day over the Atlantic.
Despite its relatively weak intensity, the storm brought very heavy rainfall over the Northeastern United States and New England, causing widespread flooding in many areas, including cities such as New York and Boston. Power outages became extensive in the region, while wind damage was sparse in comparison. In the aftermath of Henri, many crews were put in place from around the United States to help with recovery efforts and rescues. The storm caused less damage overall than initially feared, due to a weaker landfall and faster weakening trend compared to what was previously forecast. Henri continued to drop large amounts of rain as it weakened over land, prolonging floods and power outages. Henri killed two people and caused an estimated $700 million (2021 USD) in damage.
Meteorological history
A cluster of thunderstorms associated with a mid-level disturbance emerged off the U.S. Mid-Atlantic coast between late on August 11 and early the following day. The disturbance generated a weak surface trough on August 14, which by the end of that day developed into a surface low pressure area about north-northeast of Bermuda. That same day, the National Hurricane Center (NHC) mentioned the weather system as an area of potential tropical cyclogenesis, as the low drifted southward. The thunderstorms became more organized on August 15. In the early hours of August 16, the NHC classified the system as Tropical Depression Eight, while it was located about east-northeast of Bermuda. Warm sea surface temperatures favorable for the system's development were counteracted by northerly wind shear. The nascent depression moved slowly southwestward, steered around a ridge off the coast of the Eastern United States. Later that day, the depression intensified into Tropical Storm Henri, after the storm's deep convection organized further near the center.
By August 17, Henri moved westward, toward the Eastern United States. Its convection evolved into curved rainbands, and an eye feature was evident in the storm on Bermuda radar; however, it was still affected by wind shear at the time. The shear and dry air caused the storm's structure to deteriorate on August 19. On August 20, Henri turned towards the north, steering by an approaching trough over the Appalachians and a building ridge to the northeast of the storm. On August 21, at 15:00 UTC, Henri became a Category 1 hurricane after reconnaissance aircraft found hurricane-force winds. It would maintain hurricane intensity for another day, before weakening back to a high-end tropical storm at 11:00 UTC on August 22, as it approached southern New England. The storm made landfall on August 22, in Westerly, Rhode Island, around 16:15 UTC, with maximum sustained winds of . The storm rapidly weakened into a tropical depression early the next day, before becoming post-tropical. Henri's remnants persisted for another day before dissipating off the coast of Nova Scotia.
Preparations
Bermuda
At 03:00 UTC on August 16, when Tropical Depression Eight was designated, the Bermuda Weather Service issued a tropical storm watch as tropical storm conditions were possible. When Henri started to move away from Bermuda, the Bermuda Weather Service discontinued the tropical storm watch for the territory.
United States The Governor of Massachusetts Charlie Baker held a press conference on August 20. He activated 1,000 members of the Massachusetts National Guard to assist with water rescues. In Newport, Rhode Island, a beach and a road were set to be closed. Public Services crews were ordered to be on standby to respond to fallen trees. The Connecticut Department of Energy and Environmental Protection ordered campgrounds in the state to be closed from August 21 to August 23.
On August 20, Governor Ned Lamont of Connecticut declared a state of emergency ahead of the arrival of the storm. Mandatory evacuations were ordered in several communities. Storm surge, flash flooding, and high winds widespread throughout a large area were of the utmost concern preceding Henri's arrival. Hundreds of flights were delayed or cancelled at major airports across LaGuardia, John F. Kennedy, Logan, and Newark. Public transit including railway and ferries were suspended in these regions as well. On Long Island, service along the entire Greenport Branch and portions of the Montauk Branch of the Long Island Railroad were suspended.MTA suspending some LIRR, Metro-North service as Hurricane Henri approaches, Audacy, August 21, 2021 All state parks south of Interstate 84 in New York were shut down.Henri Slams Tri-State: See Latest Closures, Travel Changes, Event Cancellations, NBC New York, August 20, 2021 Inland residents were reminded that they could be hit hard as well coastal communities. Tractor trailers were banned from driving on Interstate 95 in Connecticut at 15:00 UTC on August 22. Shelters were opened around New England. In Massachusetts, storm barriers abroad were closed to protect from potential flooding. Henri was expected to move to a stall over the Connecticut–New York border, highly exacerbating floods in the areas.
New Jersey Governor Phil Murphy urged people to stay home during the storm, and advising people to look out for flooding and power lines. He made comparisons to Hurricane Sandy of 2012, which destroyed the state's coast, being thankful that Henri was not as bad as it was previously anticipated. His biggest concern was flooding in the state. President Joe Biden deployed the Federal Emergency Management Agency to help preparation efforts for Henri's damage on August 22. He also spoke with the governors of Connecticut, Rhode Island, and New York, warning about the damage that could be done by the storm. The NHC placed most of the Northeast under a flooding risk from August 22 through early August 24, warning of heavy flooding in Poconos, northern New Jersey, New York City, the Catskills, Connecticut, and western Massachusetts. The entire risk zone was expected to see of rain, with isolated double-digit totals. Flash flood watches remained in place as Henri slowed down over New England.
Up to 33 million people were still under flood warnings on August 23.
Impact United States
Power outages were widespread through most of New England due to Henri's impacts. At least 140,000 houses experienced outages across New Jersey to Maine. Conditions rapidly deteriorated the morning Henri made landfall, causing flooding in numerous locations across the Northeastern United States. By the morning of August 23, over 65,000 were still without power. Henri had weakened more quickly over land than initially expected, lessening overall impacts. Insured losses across the Northeast were estimated at $155 million by Karen Clark & Co.
New York Record-breaking rainfall of fell in just one hour in Central Park, the then-wettest hour on record for New York City. A concert which was to be held in Central Park was postponed that same night due to lightning and harsh weather. On Roosevelt Island, the Four Freedoms State Park closed due to the inclement weather. A Major League Baseball game between the New York Yankees and Minneapolis Twins was also postponed.Yankees, Twins postponed Sunday by Hurricane Henri | Reschedule date, Nj.com, August 21, 2021 A Major League Soccer game between the New York Red Bulls and New York City FC was also postponed after a two and a half hour delay.NYCFC, Red Bulls match postponed due to inclement weather, SportsNaut, August 22, 2021 The hourly rainfall record was the wettest in 150 years, and Brooklyn drivers abandoned their cars after waist-deep flooding inundated their vehicles. in total fell during August 21, the highest total in a day for the city (since 2014), while the total was the highest since Irene in 2011.
Great Gull Island clocked in a wind gust. Tuxedo Park collected , Henricks collected , and Nyack allocated . Parts of Staten Island had slightly more than of rainfall. Power outages decreased greatly on August 23, with 71 outages in Ulster County and 9 in Dutchess County. 101 of Central Hudson Gas & Electric Corp's more than 300,000 customers were without power that day. In total, a few thousand people had lost power at several points during August 21 and 22. Officials reported no flooded roads in Dutchess, though there were some fallen trees. Ulster had no reported major floods. Bronx River Parkway was closed for two days, where crews scraped off of mud. Saw Mill River Parkway was closed for two days as well.
Henri's rainfall, along with New York's 3rd wettest July, made 2021 the second-wettest summer ever in New York City; with in total (on August 23). Nearly 2 months's worth of rain fell in a day and a half in Central Park. The city's storm-sewer system, which can only handle about daily, had over fall into it from Henri from August 21–22. Videos taken in the subway system showed rain pouring down, these led to a few disruptions in service.
Rhode Island On the morning of August 22, over 58,000 people were without power in Rhode Island, with outages being particularly widespread in Washington County. Wind gusts reached over . Trees and power lines were downed from the storm. Newport was spared from the worst of the storm. A sailboat named Paws washed up to shore in the city, however, its owner was not found. In Cranston, there were 11 inches of rainfall, causing flooding. Nearly 41,000 people were still without power the morning of August 23. 75 percent of the town of South Kingstown lost power on August 22. The state was to have been hit an estimated 15 to 20 percent harder in power outages than Massachusetts and Connecticut.
New Jersey In New Jersey, more than of rain fell in the town of Cranbury. Up to of rain fell in the state, bringing heavy flooding in multiple areas, such as Jamesburg, where heavy rain caused flooding on roads. Numerous roads were closed in Middlesex, with vehicles submerged in floodwaters. Homes were flooded with up to of water in Cranbury, and some residences and businesses were flooded in Milltown. During the early afternoon of August 22, over 4,500 were reported without power in the state. Some places were flooded with up of water, and left behind of mud.